1. Field of the Invention
The present invention generally relates to liquid drop jet heads and ink jet recording apparatuses, and more particularly, to a liquid drop jet head used for an ink jet recording apparatus and the ink jet recording apparatus used as a picture recording apparatus or picture forming apparatus.
2. Description of the Related Art
An ink jet recording apparatus is used as a picture forming apparatus or picture recording apparatus such as a printer, facsimile, or copy machine. An ink jet head is used for the ink jet recording apparatus as a liquid drop jet head. The ink jet head includes a nozzle, a liquid room, and a pressure generating means. An ink drop is jetted out by the nozzle. The nozzle is connected to the liquid room. The liquid room is called a pressurized liquid room, pressure room, jet room, or ink channel. The ink in the liquid room is pressurized by the pressure generating means. The ink drop is jetted out from the nozzle due to the pressure in the liquid room generated by the pressure generating means.
There are several types of ink jet heads such as a piezo type, a bubble type (thermal type) or an electrostatic type. In the piezo type ink jet head, the ink drop is jetted out by deforming or displacing a vibration board forming a wall surface of the liquid room with a electric machine conversion element such as a piezoelectric element. In the bubble type ink jet head, the ink drop is jetted out by a bubble generated by boiling an ink film with an electric heat conversion element. In the static electricity type ink jet head, the ink drop is jetted out by deforming the vibration board with an electrostatic force caused by the vibration board (or an electrode united with the vibration board) forming the wall surface of the liquid room and an electrode facing the vibration board.
In a related art ink jet head, a liquid room and a common liquid room connected to the liquid room are made of photosensitive resin, resin mold, metal, glass or others. However, since the liquid room made of resin has low rigidity, cross talk is apt to occur between neighboring liquid rooms so that it is not possible to obtain a high quality picture. On the other hand, a liquid room made of metal or glass has high rigidity so that the problem regarding cross talk is small. However, since it is difficult for the liquid room made of metal or glass to be processed, it is difficult to meet a demand that the ink jet head have a high density to obtain a high quality picture.
In order to solve the above mentioned problems, for example, it is proposed to form the liquid room or the common liquid room by anisotropic-etching of a silicon substrate (silicon wafer), in Japanese Laid-Open Patent Applications No. 7-132595 and No. 7-276626. The silicon has a high rigidity and can be fine-processed by anisotropic-etching. Particularly, it is possible to form a perpendicular wall surface by using the silicon wafer of a surface direction of (110), so that the liquid room can be arranged with high density.
FIG. 1 is a plan view for explaining a configuration of the liquid room of a related art ink jet head. The liquid room structure of the related art shown in FIG. 1 is made by anisotropic-etching of the silicon substrate of the surface direction of (110). Plural liquid rooms 201, a common liquid room 202 and an ink supply opening part 203 are arranged in the liquid room structure. Each of the liquid rooms 201 has a configuration of a parallelogram on a plane level. The common liquid room 202 has a polygonal configuration consisting of plural parallelograms on a plane level. The common liquid room 202 is connected to the liquid rooms 201 by a fluid resister part (ink supply channel) not shown in FIG. 1. The ink is supplied from outside of the ink jet head to the common room 202 by the ink supply opening part 203.
When the liquid room 201 or the common liquid room 202 is formed by anisotropic-etching of the silicon substrate, the configuration of the liquid room 201 or the common liquid room 202 is formed only in a direction along a crystal direction due to anisotropy of the silicon substrate. Therefore, although the liquid rooms 201 are formed at a side of the direction along the crystal direction of the silicon substrate, the common liquid room 202 having a larger area than the liquid rooms 201 has a configuration tightly consisting of the tightly spaced plural parallelograms formed to a direction of the row of the liquid rooms 201. Therefore, as shown in FIG. 1, the common liquid room 202 has wall surface parts 202a and 202b which are along the row of the liquid rooms 201 and which have a configuration of saw teeth.
Meanwhile, a bubble often gets into the liquid room or the common liquid room in the ink jet head, when an ink tank is exchanged or due to an external vibration. Because of this, a bubble discharge method is applied as an operation for recovering reliability in an ink jet recording apparatus. In the method, the ink is absorbed from the nozzle or an outlet for the bubble, so that the bubble is removed together with the ink.
However, as described above, the wall surface of the common liquid room has the configuration of the saw teeth on a plane level. Therefore, a current speed of the ink supplied from the ink supply opening part 203 is reduced by the wall surfaces 202a and 202b of the common room 202. As a result, a bubble B adheres to a corner part of the wall surfaces 202a and 202b, the wall surfaces 202a and 202b having the configuration of saw teeth, so that the bubble B is not discharged. The bubble B may be left even if the bubble discharge method is applied as the operation for recovering reliability.
In this case, a bubble discharge may be improved by cutting the corner part of the wall surfaces 202a and 202b obliquely. However, there is a still problem in that the speed of the ink is reduced at an area remote from the ink supply opening part 203 by the wall surfaces 202a and 202b having the configuration of saw teeth during the operation the bubble discharge method. As a result, it is not possible to discharge the bubble completely.
Furthermore, during the ink jet operation, the ink is not sufficiently supplied to a liquid room remote from the ink supply opening part 203 so that bad jetting may result.
In addition, generally, a common liquid room connected to plural liquid rooms has a large opening area. Particularly, the opening area is further increased as the number of the nozzles increases for the high density and high speed recording. As a result, the strength of the ink jet head is reduced so that a yield rate is reduced due to damage of the ink jet head during assemble.
Furthermore, the common liquid room has a large opening part. Therefore, when a nozzle board is connected, the nozzle board is bent, damaged, or incorrectly-connected due to a non-uniform load while connecting, at the common liquid room.
Accordingly, it is a general object of the present invention to provide a novel and useful liquid drop jet head, ink cartridge, and ink jet recording apparatus in which one or more of the problems described above are eliminated.
Another and more specific object of the present invention is to provide a liquid drop jet head, by which a bubble saved in a common liquid room is discharged smoothly, and by which liquid is supplied to all liquid rooms sufficiently and stable jetting of a liquid drop is implemented during an operation of jetting of the liquid drop. It is also the object of the present invention to provide an ink cartridge into which the liquid drop jet head is integrated, and an ink jet recording apparatus where the liquid drop jet head is loaded.
The above objects of the present invention are achieved by a liquid drop jet head, including a nozzle jetting a liquid drop, a liquid room connected to the nozzle, a common liquid room connected to the liquid room, a supply opening part supplying the liquid to the common liquid room, and a pressure generating part that generates a pressure pressurizing the liquid provided in the liquid room, wherein the common liquid room has a configuration in which a width of the common liquid room on a plane level is narrower as a point of the width is more remote from the supply opening part.
According to the present invention as described above, it is possible to prevent a flow speed of a liquid from slowing so that a bubble can be discharged smoothly. Hence, bad jetting of a drop can be prevented.
The width of the common liquid room on the plane level may be narrower substantially consecutively as the point of the width is more remote from the supply opening part. The width of the common liquid room on the plane level may be narrower substantially gradually as the point of the width is more remote from the supply opening part.
According to the present invention as described above, it is possible to obtain a smooth flow of the liquid and prevent the flow speed of the liquid from reducing. Hence, bad jetting of a drop can be prevented.
The common liquid room may have a configuration of a single wing on a plane level.
According to the present invention as described above, it is possible to obtain a smooth flow of the liquid and prevent the flow speed of the liquid from reducing. Hence, bad jetting of a drop can be prevented.
The supply opening part may be provided at a wall surface side opposite side to the liquid room in the common liquid room, an external side of the wall surface, or an external side of the liquid room in a direction of a line of the liquid room.
According to the present invention as described above, it is possible to prevent the bubble from being stagnated between the supply opening part and the wall surface.
The common liquid room may have a configuration of dual wings on a plane level.
According to the present invention as described above, it is possible to obtain the smooth flow of the liquid supplied from one supply opening part in a wider range than in a single wing configuration. Hence, it is possible to jet the liquid stably.
A wall surface opposite to the side to which the liquid room is provided in a common liquid room may have a substantially arc configuration or a semicircle configuration in a direction of a line.
According to the present invention as described above, it is possible to flow the liquid from the supply opening part symmetrically, so that it is possible to obtain stable drop jetting.
The supply opening part may be provided at a wall surface side opposite to the side to which the liquid room is provided in the common liquid room, an external side of the wall surface, or an external side of the liquid room being in a direction of a line of the liquid room.
According to the present invention as described above, it is possible to prevent the bubble from being stagnated between the supply opening part and the wall surface.
A plurality of common liquid rooms may be formed in a direction of a line of the liquid rooms independently.
According to the present invention as described above, since the distance between the supply opening part and the liquid room is short, the reduction of the flow speed of the liquid can be reduced. Hence, it is possible to discharge the bubble smoothly and supply the liquid sufficiently at the time of jetting. In addition, since an area of the opening part of one common liquid room is narrow, it is possible to reduce damage or incorrect-connections at the time of assembling so that it is possible to improve a yield rate.
A plurality of the common liquid rooms may be formed in a direction of a line of the liquid rooms independently and the respective common liquid rooms are arranged in parallel.
According to the present invention as described above, it is possible to arrange the supply opening part at an external part of a narrow width part of the neighboring common liquid room. Hence, it is possible to make the capacity of the common liquid room large with a reasonable space.
A plurality of the common liquid rooms may be formed in a direction of a line of the liquid rooms independently and the respective common liquid rooms are arranged line-symmetrically.
According to the present invention as described above, it is possible to supply the liquid from one supply opening part to the independent common liquid room. Furthermore, when a plural line of the nozzles are made, the liquid is supplied from the supply opening part to the common liquid room in the respective lines.
A number of the liquid rooms connected to one of the common liquid room may be in a range of two or more and thirty-two or less.
According to the present invention as described above, it is possible to discharge the bubble accurately.
The respective common liquid rooms and the liquid rooms may have partition walls and a width of the partition wall between the neighboring common liquid rooms has the substantially same length as the width of the partition wall between the neighboring liquid rooms.
According to the present invention as described above, it is possible to maintain the strength of the partition wall so that it is possible to part the common liquid room between the neighboring liquid rooms.
The liquid rooms may make a plurality of lines and the common liquid rooms for the every line of the liquid rooms are provided independently between the respective lines of the liquid rooms.
According to the present invention as described above, it is possible to increase the nozzle density so that it is possible to record with a high quality.
The supply opening part being common for the common liquid rooms for the every line of the liquid rooms may be provided in the common liquid rooms so that the liquid is supplied.
According to the present invention as described above, it is possible to make the structure of liquid drop jet head easily.
The common liquid room may be formed by anisotropic-etching of a silicon substrate.
According to the present invention as described above, it is possible to reduce the cross talk and arrange the liquid room with a high density. Hence, it is possible to record with a high density.
The common liquid room may have a wall surface at a liquid room side of the common liquid room, and the wall surface has a plane configuration having an obtuse angle.
According to the present invention as described above, it is possible to obtain a smooth flow of the liquid and improve the bubble discharge.
The supply opening part may be provided at a surface opposite side to a lid member or a nozzle board forming a wall surface of the liquid room.
According to the present invention as described above, it is possible to make a structure at a surface side near the nozzle easily so that it is possible to miniaturize the jet head.
The supply opening part may be formed by a mechanical process.
According to the present invention as described above, it is possible to select a configuration of the supply opening part widely.
The supply opening part may be formed by anisotropic-etching.
According to the present invention as described above, it is possible to form plural supply opening parts at the same time so that it is possible to reduce the cost.
The pressure generating part may include a vibration board forming the wall surface of the liquid room and an electrode facing the pressure generating part so that the vibration board is deformed by an electrostatic force.
According to the present invention as described above, it is possible to make a high density of the heads easily regardless of the nature of the liquid.
The pressure generating part may include a vibration board forming the wall surface of the liquid room and an electric machine conversion element deforming the vibration board.
According to the present invention as described above, it is possible to make the head regardless of the nature of the liquid.
The pressure generation part may include an electric thermal conversion element arranged in the liquid room.
According to the present invention as described above, it is possible to make the heads of a high density easily.
The liquid drop jet head may be used as an ink jet head, for an ink cartridge in which an ink tank supplying the ink to the ink jet head is unified.
According to the present invention as described above, it is possible to reduce bad jetting due to bubble stagnation so that it is possible to realize operations at low cost.
It is also another object of the present invention to provide an ink jet recording apparatus, comprising an ink jet head jetting the ink drop, the ink jet head includes a nozzle jetting a liquid drop, a liquid room connected to the nozzle, a common liquid room connected to the liquid room, a supply opening part supplying the liquid to the common liquid room, and a pressure generating part which generates a pressure pressurizing the liquid provided in the liquid room, wherein the common liquid room has a configuration in which a width of the common liquid room on a plane level is narrower as a point of the width is more remote from the supply opening part.
According to the present invention as described above, it is possible to obtain a stable operation of the ink drop jet so as to avoid bad jetting. As a result, picture quality improves and the amount of ink absorbed to discharge the bubbles is small. Hence, it is possible to avoid useless consumption of the ink.
Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.